Large band splitting with tunable spin polarization in the two-dimensional ferroelectric GaXY family (X=Se,Te; Y=Cl,Br,I)

Moh. Adhib Ulil Absor and Fumiyuki Ishii
Phys. Rev. B 103, 045119 – Published 19 January 2021

Abstract

It has been generally accepted that the spin-orbit coupling effect in noncentrosymmetric materials leads to the band splitting and nontrivial spin polarization in the momentum space. However, in some cases, zero net spin polarization in the split bands may occurs, dubbed as the band splitting with vanishing spin polarization (BSVSP) effect, protected by non-pseudo-polar point group symmetry of the wave vector in the first Brillouin zone [K. Liu et al., Nat. Commun. 10, 5144 (2019)]. In this paper, by using first-principles calculations, we show that the BSVSP effect emerges in two-dimensional (2D) nonsymmorphic GaXY (X= Se, Te; Y= Cl, Br, I) family, a new class of 2D materials having in-plane ferroelectricity. Taking the GaTeCl monolayer as a representative example, we observe the BSVSP effect in the split bands along the XM line located in the proximity of the conduction band minimum. By using the k·p Hamiltonian derived based on the symmetry analysis, we clarify that such an effect originates from the cancellation of the local spin polarization, enforced by non-pseudo-polar C2v point group symmetry of the wave vector along the XM line. Importantly, we find that the spin polarization can be effectively induced by applying an external out-of-plane electric field, indicating that an electrically tunable spin polarization for spintronic applications is plausible.

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  • Received 12 October 2020
  • Revised 13 December 2020
  • Accepted 5 January 2021

DOI:https://doi.org/10.1103/PhysRevB.103.045119

©2021 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Moh. Adhib Ulil Absor*

  • Department of Physics, Universitas Gadjah Mada, Sekip Utara, BLS 21 Yogyakarta, Indonesia

Fumiyuki Ishii

  • Nanomaterials Research Institute, Kanazawa University, 920-1192 Kanazawa, Japan

  • *adib@ugm.ac.id

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Vol. 103, Iss. 4 — 15 January 2021

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